Photographic developers



United States Patent Oflice 3,255,890 Patented August 16, 1966 3,266,899 PHQTQGRAPHEC DEVELGPERS David William Crichton Ramsay, Sale, England, assignor to Ilford Limited, llford, England, a British company No Drawing. Filed Jan. 16, 1964, Ser. No. 338,015 Claims priority, application Great Britain, Jan. 21, 1963,

8 Claims. (Cl. 96-66) This invention relates to photographic developing compositions.

It is known that certain chemical compounds which used alone are poor developers for photographic silver halide emulsions become much more effective when used in conjunction with other developers, the effect being known as supera-dditivity. Thus, for example p-methylaminophenol and 1-phenyl-3-pyraz0lidone show the phenomenon of superadditivity when either is used in conjunction with hydroquinone, hydroxyphenyl glycine, ascorbic acid or other photographic developing substances.

It is an object of the present invention to provide new photographic developing compositions which exhibit the said phenomenon of superadditivity.

According to the present invention there is provided a developing composition which comprises a developing substance of the general formula:

where x and y are the same or different and each is nought or one and Z and Z are the same or different and are each the atoms or groups necessary to complete a heterocyclic nitrogen ring, or an acid addition salt thereof, a second developing substance (preferably hydroquinone) which with the compound of the said formula exerts a superadditive effect, the composition when dissolved in water affording an alkaline solution.

The invention includes the compositions in solid form suitable for dilution with water and optionally addition of other ingredients to make a developer solution suitable for use, concentrated aqueous solutions of the normally solid constituents and the aqueous solutions ready for use. It further includes the process of making photographic records by developing, with such solutions, photographic materials having layers containing developable silver salts.

In the foregoing general formula the values of x, y, Z and Z may be selected to be such that the nitrogen ring systems may be, for example, pyridine, pyrroline, quinoline or thiazoline systems.

Instead of hydroquinone there may be employed chlorhydroquinone or other developers, e.g. those known from the literature to afford a superadditive effect with l-phenyl- 3-pyrazolidone.

The developer solutions for use should be alkaline and it is often desirable to provide that the pH value is above 9 and preferably above 11.

A typical compound of the foregoing general formula for use in the present invention is 5,5-hydrazo-2,2-2',2 tetramethyl-l,1'-pyrroline-l,1-dioxide, of the formula:

which may be prepared by the method described in Proceedings of the Chemical Society, 1962, p. 360.

The following examples will serve to illustrate the invention:

Example 1 The following developing composition is formulated:

. G. 5:5 hydrazo-Z 2-2 2'-tetramethyl-1 l'-pyrroline- 1: 1-dioxide 3.9 Hydroquinone 8.0 Sodium sulphite (an-hydrous) Sodium carbonate (anhydrous) 37.5 Potassium bromide 2.0 Potassium hydroxide 60 Water to make 1 litre.

The compounds CH2CH2 GHQ-CH2 3 I I I! Naphthalene disulplionie acid salt m J. NH-NH were each dissolved at a concentration of 0.04 centimole per litre in a solution of the following composition:

Hydroquinone g 1.46 Sodium sulphite (anhydrous) g 6.75 Sodium hydroxide g 1.30 Potassium bromide g 0.25 Ethylene diamine tetra-acetic acid, disodium salt g 0.60 Benzotriazole (1% solution) ml 0.95 Water to make ml 1000 The pH of this solution was 12.

Sensitometrically exposed high speed panchromatic negative material was processed for 4 and 7 minutes at 20 C. in these solutions. Comparison of the characteristic curves obtained with curves from the material similarly processed in the solution without compound (1) or (2), showed that the addition of these compounds had produced increases in speed over the valve obtained with hydroquinone alone. The differences are shown in the following table:

Dcvelop- Speed increase Compound ment time, log exposure Gamma mins. units 2: 2 hydrazo-l,1'-pyridine-1,1'-dioxide, may be prepared by the following method.

Z-nitropyridine-l-oxide (0.5 g.) is dissolved in absolute alcohol (50 ml.) and hydrogenated at 20 C. over a 2% palladiurn/ strontium carbonate catalyst (0.2 g.) at a pressure of 1 atmosphere, the reduction is stopped when the theoretical volume of hydrogen (215 ml.) has been absorbed. The catalyst is removed from the solution by filtration and the filtrates evaporated to dryness under reduced pressure. The residue is slurried in dry acetone and the crude 2:2'-hydrazo-1,1-pyridine-1,1'-dioxide collected.

After recrystallisation from absolute ethanol 2:2'-hydrazo-l,1-pyridine-1,1'-dioxide (0.1 g.) is obtained, melting point 158-161 C. (decomp.).

I claim as my invention:

1. A developing composition which comprises essentially a developing substance of the formula:

where x and y are each selected from nought and one and Z and Z are each the residues necessary to complete a heterocyclic nitrogen ring and, as a second developing substance, a substance known to exert a superadditive effeet on l-phenyl-3-pyrazolidone, the composition when dissolved in water affording an alkaline solution.

2. A developing composition as in claim 1 wherein the heterocyelic nitrogen ring is selected from the class consisting of pyridine, pyrroline, quinoline and thiazoline.

3. A developing composition as in claim 1 wherein the second developing substance is selected from the class consisting of hydroquinone, chlorhydroquinone, hydroxyphenyl glycine and ascorbic acid.

4. A developing composition as in claim 1 wherein the composition is in solid form suitable for dilution with water to make a developer solution.

5. A developing composition as in claim 1 wherein the composition is in the form of a concentrated aqueous solution suitable for dilution with water to make a developer solution.

6. A developing composition as in claim 1 wherein the pH of the composition dissolved in water is above 11.

7. A developing composition which comprises 5,5'-hydrazo-2,2-2,2-tetramethyl-l,1'-pyrr0line-l,1'-dioxide and hydroquinone, the composition when dissolved in water affording an alkaline solution.

8. A developing composition which comprises 2:2'-hydrazo-1,1-pyridine-l,l'-dioxide and hydroquinone, the composition when dissolved in water affording an alkaline solution.

No references cited.

NORMAN G. TORCHIN, Primary Examiner.

CAROLYN DAVIS, Assistant Examiner. 

1. A DEVELOPING COMPOSITION WHICH COMPRISES ESSENTIALLY A DEVELOPING SUBSTANCE OF THE FORMULA: 